The invention relates to a primary-beam collimator for a stereo radiographic x-ray diagnostic installation with an x-ray tube having dual focal points spaced at a distance from each other.
In such an arrangement the object under study is x-rayed alternately from each of the focal points. By simultaneously viewing the radiograph pair--obtained from two focal points--the observer perceives a spatial image. The use of such multifocal x-ray tubes presents the problem of ensuring adequate x-ray exposure of the relevant areas of the object examined, as sourced from each of the two focal points, while avoiding the exposure of more tissue than is required.